Add serial and firmware to the extra data

And add the missing newline to the debug output to help us identify
encodings for serial and firmware.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Improve Uemis debug output for short data blocks

It's useful to know just how short the read was when trying to figure out
what went wrong.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
Correct Uemis extra data

When dropping the pointless surface samples at the end of the dive we
stopped going through all the samples - for that reason the offset at the
end to find the data in the footer was wrong.

Now the extra data all seems to match what I can see on my screen after
the dive.

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>